Multichannel analysis of normal and continuous adventitious respiratory sounds for the assessment of pulmonary function in respiratory diseases

Premi extraordinari doctorat UPC curs 2015-2016, àmbit d’Enginyeria IndustrialRespiratory sounds (RS) are produced by turbulent airflows through the airways and are inhomogeneously transmitted through different media to the chest surface, where they can be recorded in a non-invasive way. Due to their mechanical nature and airflow dependence, RS are affected by respiratory diseases that alter the mechanical properties of the respiratory system. Therefore, RS provide useful clinical information about the respiratory system structure and functioning. Recent advances in sensors and signal processing techniques have made RS analysis a more objective and sensitive tool for measuring pulmonary function. However, RS analysis is still rarely used in clinical practice. Lack of a standard methodology for recording and processing RS has led to several different approaches to RS analysis, with some methodological issues that could limit the potential of RS analysis in clinical practice (i.e., measurements with a low number of sensors, no controlled airflows, constant airflows, or forced expiratory manoeuvres, the lack of a co-analysis of different types of RS, or the use of inaccurate techniques for processing RS signals). In this thesis, we propose a novel integrated approach to RS analysis that includes a multichannel recording of RS using a maximum of five microphones placed over the trachea and the chest surface, which allows RS to be analysed at the most commonly reported lung regions, without requiring a large number of sensors. Our approach also includes a progressive respiratory manoeuvres with variable airflow, which allows RS to be analysed depending on airflow. Dual RS analyses of both normal RS and continuous adventitious sounds (CAS) are also proposed. Normal RS are analysed through the RS intensity–airflow curves, whereas CAS are analysed through a customised Hilbert spectrum (HS), adapted to RS signal characteristics. The proposed HS represents a step forward in the analysis of CAS. Using HS allows CAS to be fully characterised with regard to duration, mean frequency, and intensity. Further, the high temporal and frequency resolutions, and the high concentrations of energy of this improved version of HS, allow CAS to be more accurately characterised with our HS than by using spectrogram, which has been the most widely used technique for CAS analysis. Our approach to RS analysis was put into clinical practice by launching two studies in the Pulmonary Function Testing Laboratory of the Germans Trias i Pujol University Hospital for assessing pulmonary function in patients with unilateral phrenic paralysis (UPP), and bronchodilator response (BDR) in patients with asthma. RS and airflow signals were recorded in 10 patients with UPP, 50 patients with asthma, and 20 healthy participants. The analysis of RS intensity–airflow curves proved to be a successful method to detect UPP, since we found significant differences between these curves at the posterior base of the lungs in all patients whereas no differences were found in the healthy participants. To the best of our knowledge, this is the first study that uses a quantitative analysis of RS for assessing UPP. Regarding asthma, we found appreciable changes in the RS intensity–airflow curves and CAS features after bronchodilation in patients with negative BDR in spirometry. Therefore, we suggest that the combined analysis of RS intensity–airflow curves and CAS features—including number, duration, mean frequency, and intensity—seems to be a promising technique for assessing BDR and improving the stratification of BDR levels, particularly among patients with negative BDR in spirometry. The novel approach to RS analysis developed in this thesis provides a sensitive tool to obtain objective and complementary information about pulmonary function in a simple and non-invasive way. Together with spirometry, this approach to RS analysis could have a direct clinical application for improving the assessment of pulmonary function in patients with respiratory diseases.Los sonidos respiratorios (SR) se generan con el paso del flujo de aire a través de las vías respiratorias y se transmiten de forma no homogénea hasta la superficie torácica. Dada su naturaleza mecánica, los SR se ven afectados en gran medida por enfermedades que alteran las propiedades mecánicas del sistema respiratorio. Por lo tanto, los SR proporcionan información clínica relevante sobre la estructura y el funcionamiento del sistema respiratorio. La falta de una metodología estándar para el registro y procesado de los SR ha dado lugar a la aparición de diferentes estrategias de análisis de SR con ciertas limitaciones metodológicas que podrían haber restringido el potencial y el uso de esta técnica en la práctica clínica (medidas con pocos sensores, flujos no controlados o constantes y/o maniobras forzadas, análisis no combinado de distintos tipos de SR o uso de técnicas poco precisas para el procesado de los SR). En esta tesis proponemos un método innovador e integrado de análisis de SR que incluye el registro multicanal de SR mediante un máximo de cinco micrófonos colocados sobre la tráquea yla superficie torácica, los cuales permiten analizar los SR en las principales regiones pulmonares sin utilizar un número elevado de sensores . Nuestro método también incluye una maniobra respiratoria progresiva con flujo variable que permite analizar los SR en función del flujo respiratorio. También proponemos el análisis combinado de los SR normales y los sonidos adventicios continuos (SAC), mediante las curvas intensidad-flujo y un espectro de Hilbert (EH) adaptado a las características de los SR, respectivamente. El EH propuesto representa un avance importante en el análisis de los SAC, pues permite su completa caracterización en términos de duración, frecuencia media e intensidad. Además, la alta resolución temporal y frecuencial y la alta concentración de energía de esta versión mejorada del EH permiten caracterizar los SAC de forma más precisa que utilizando el espectrograma, el cual ha sido la técnica más utilizada para el análisis de SAC en estudios previos. Nuestro método de análisis de SR se trasladó a la práctica clínica a través de dos estudios que se iniciaron en el laboratorio de pruebas funcionales del hospital Germans Trias i Pujol, para la evaluación de la función pulmonar en pacientes con parálisis frénica unilateral (PFU) y la respuesta broncodilatadora (RBD) en pacientes con asma. Las señales de SR y flujo respiratorio se registraron en 10 pacientes con PFU, 50 pacientes con asma y 20 controles sanos. El análisis de las curvas intensidad-flujo resultó ser un método apropiado para detectar la PFU , pues encontramos diferencias significativas entre las curvas intensidad-flujo de las bases posteriores de los pulmones en todos los pacientes , mientras que en los controles sanos no encontramos diferencias significativas. Hasta donde sabemos, este es el primer estudio que utiliza el análisis cuantitativo de los SR para evaluar la PFU. En cuanto al asma, encontramos cambios relevantes en las curvas intensidad-flujo yen las características de los SAC tras la broncodilatación en pacientes con RBD negativa en la espirometría. Por lo tanto, sugerimos que el análisis combinado de las curvas intensidad-flujo y las características de los SAC, incluyendo número, duración, frecuencia media e intensidad, es una técnica prometedora para la evaluación de la RBD y la mejora en la estratificación de los distintos niveles de RBD, especialmente en pacientes con RBD negativa en la espirometría. El método innovador de análisis de SR que se propone en esta tesis proporciona una nueva herramienta con una alta sensibilidad para obtener información objetiva y complementaria sobre la función pulmonar de una forma sencilla y no invasiva. Junto con la espirometría, este método puede tener una aplicación clínica directa en la mejora de la evaluación de la función pulmonar en pacientes con enfermedades respiratoriasAward-winningPostprint (published version

Cryoablation of cardiac arrhythmias

This thesis evaluates the safety and efficacy of cryoablation in supraventricular tachyarrhythmias. In Study I, the acute and long-term outcome of cryoablation therapy of typical atrioventricular nodal reentrant tachycardia (AVNRT) was studied in a large series of patients (n=312). Acute procedural success in AVNRT with cryoablation was achieved in 99% of patients with a recurrence rate of 5.8% during a mean follow-up period of 22 months, which is similar to the expected outcome after radiofrequency ablation (RF). There were no long-term complications related to the use of cryoablation. Additionally, it was shown that further reduction of the recurrence rate may be achieved by using the endpoint of complete slow pathway elimination compared with residual slow pathway conduction. In Study II the clinical usefulness of cryoenergy for the ablation of perinodal atrioventricular reentrant tachycardia (AVRT) was investigated. Cryomapping of substrates adjacent to the AV-node may improve safety of the procedure. Acute procedural success with cryoablation in superoparaseptal and septal accessory pathways was achieved in 96% of the patients with a recurrence rate of 27% during a median follow-up of 33 months. The total success rate was 89% after a second cryoablation. Thus, acute and long-term results were similar to those reported for RF but without any complications related to the conducting system. In Study III the safety and efficacy of cryoablation of atrial tachycardia (AT) with high risk of ablation-related injuries was evaluated. AT foci originated from the para-hisian area, the vicinity of the sinus node, and the crista terminalis adjacent to the phrenic nerve were studied. Acute procedural success was achieved in 96% of patients with a recurrence rate of 12% during a mean follow-up period of 16 months. The total success rate after a second cryoablation was 92%, which is similar to that reported for RF ablation but without any permanent complications. In Study IV cryoablation was compared to RF ablation for the treatment of cavotricuspid isthmusdependent atrial flutter with emphasis on clinical success, safety, and procedure-related pain. The acute ablation success was 95% in the RF group and 92% in the cryoablation group (NS). The long-term success after six-month of follow-up was 92% for RF and 86% for cryoablation (NS). RF ablation caused significantly more pain compared to cryoablation both in terms of average and peak pain perception. In conclusion, cryoablation of AVNRT, of high risk AVRT, and of AT are safe and effective alternatives to RF ablation without causing any permanent complication related to the conducting system and the phrenic nerve. Moreover, cryoablation of isthmus-dependent atrial flutter is not inferior to RF but with less procedure-related pain

Current Issues and Recent Advances in Pacemaker Therapy

Patients with implanted pacemakers or defibrillators are frequently encountered in various healthcare settings. As these devices may be responsible for, or contribute to a variety of clinically significant issues, familiarity with their function and potential complications facilitates patient management. This book reviews several clinically relevant issues and recent advances of pacemaker therapy: implantation, device follow-up and management of complications. Innovations and research on the frontiers of this technology are also discussed as they may have wider utilization in the future. The book should provide useful information for clinicians involved in the management of patients with implanted antiarrhythmia devices and researchers working in the field of cardiac implants

Respiratory Control: Central and Peripheral Mechanisms

Understanding of the respiratory control system has been greatly improved by technological and methodological advances. This volume integrates results from many perspectives, brings together diverse approaches to the investigations, and represents important additions to the field of neural control of breathing. Topics include membrane properties of respiratory neurons, in vitro studies of respiratory control, chemical neuroanatomy, central integration of respiratory afferents, modulation of respiratory pattern by peripheral afferents, respiratory chemoreception, development of respiratory control, behavioral control of breathing, and human ventilatory control. Forty-seven experts in the field report research and discuss novel issues facing future investigations in this collection of papers from an international conference of nearly two hundred leading scientists held in October 1990. This research is of vital importance to respiratory physiologists and those in neurosciences and neurobiology who work with integrative sensory and motor systems and is pertinent to both basic and clinical investigations. Respiratory Control is destined to be widely cited because of the strength of the contributors and the dearth of similar works. The four editors are affiliated with the University of Kentucky: Dexter F. Speck is associate professor of physiology and biophysics, Michael S. Dekin is assistant professor of biological sciences, W. Robert Revelette is research scientist of physiology and biophysics, and Donald T. Frazier is professor and chairman of physiology and biophysics. Experts in the field report current research and discuss novel issues facing future investigations. —SciTech Book Newshttps://uknowledge.uky.edu/upk_biology/1002/thumbnail.jp

Difficulties with Ablation for Arrhythmias in Children

Radiofrequency ablation procedures in children present unique challenges for the electrophysiologist. At times, obtaining vascular access to reach the heart is a problem. If this first step is accomplished, the small size of the child's heart, arrhythmias relatively unique to the pediatric population, and the presence of congenital heart disease add to the complexity

Advances in Clinical Neurophysiology

Including some of the newest advances in the field of neurophysiology, this book can be considered as one of the treasures that interested scientists would like to collect. It discusses many disciplines of clinical neurophysiology that are, currently, crucial in the practice as they explain methods and findings of techniques that help to improve diagnosis and to ensure better treatment. While trying to rely on evidence-based facts, this book presents some new ideas to be applied and tested in the clinical practice. Advances in Clinical Neurophysiology is important not only for the neurophysiologists but also for clinicians interested or working in wide range of specialties such as neurology, neurosurgery, intensive care units, pediatrics and so on. Generally, this book is written and designed to all those involved in, interpreting or requesting neurophysiologic tests